Prediction of the strength properties of ceramic composites with allowance for the effect of residual processing stresses

1993 ◽  
Vol 28 (5) ◽  
pp. 461-463
Author(s):  
A. L. Maistrenko ◽  
N. V. Lamashevskaya
Keyword(s):  
Ceramic Composites ◽  
Strength Properties ◽  
Residual Processing

Microstructure and Properties of the Composites: Hydroxyapatite With Addition of Zirconia Phase

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Agata Dudek
Keyword(s):  
Ceramic Composites ◽  
Strength Properties ◽  
Yttria Stabilized Zirconia ◽  
Cubic Phase ◽  
Stabilized Zirconia ◽  
Zirconia Ceramics ◽  
Solid State Ionics ◽  
Hydroxyapatite Composite ◽  
Recent Trends ◽  
Zirconia Phase

The group of bioceramics includes hydroxyapatites, which, due to their specific properties, are widely used in biotechnology. These compounds exist in skeletons of human and animal bodies. A range of advantages of implants, which contain, among other things, hydroxyapatites, results also from the level of their porosity. Recent trends that focus on the improvement in poor strength properties of HA coatings include the introduction of solid solution of Y2O3 in ZrO2 (Khalil et al., 2007, “Consolidation and Mechanical Properties of Nanostructured Hydroxyapatite Bioceramics by High Frequency Induction Heat Sintering,” Mater. Sci. Eng., 456, pp. 368–372; Chevalier et al., 2004, “Critical Effect of Cubic Phase on Aging in 3 mol % Yttria-Stabilized Zirconia Ceramics for Hip Replacement Prothesis,” Biomaterials, 25, pp. 5539–5545; Inuzuka et al., 2004, “Hydroxyapatite-Deped Zirconia for Preparation of Biomedical Composites Ceramics,” Solid State Ionics, 172, pp. 509–513; Sung, Y. M., and Kim, D. H., 2003, “Crystallization Characteristics of Yttria-Stabilized Zirconia/Hydroxyapatite Composite Nanopowder,” J. Cryst. Growth, 254, pp. 411–417; Marciniak, J., 2002, Biomateriały, Wydawnictwo Politechniki Śląskiej, Gliwice, Poland; Park J., and Bronzino J. D., 2000, Biomaterials, CRC, Boca Raton, FL; Yoshida et al., 2006, “Fabrication of Structure-Controlled Hydroxyapatite/Zirconia Composite,” J. Eur. Ceram. Soc., 26, pp. 515–518). It seems essential to determine the resulting structural and strength properties in the aspect of further application of composites based on hydroxyapatite with the addition of the zirconia phase. The investigations involved ceramic composites based on HA with different amounts of the phase modified with ZrO2 yttrium dioxide.

SiAlON-TiN Ceramic Composites by Electric Current Assisted Sintering

2019 ◽  
Vol 946 ◽  
pp. 53-57
Author(s):  
Konstantin L. Smirnov ◽  
E.G. Grigoryev ◽  
E.V. Nefedova
Keyword(s):  
Electric Current ◽  
Spark Plasma Sintering ◽  
Electric Discharge ◽  
Raw Materials ◽  
Ceramic Composites ◽  
Strength Properties ◽  
Promising Technique ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
High Level

Electric current assisted sintering of β-Si5AlON7-TiN ceramic composites from raw materials prepared by combustion synthesis was investigated. A high level of relative density (92% and higher) was achieved by using of two types of electric current assisted sintering technique: high voltage electric discharge consolidation, as well as spark plasma sintering. While only spark plasma sintering, it may be considered as promising technique for obtaining ceramic composites and items with high level of strength properties.

Study of the fracture features of layered ceramics in its microvolumes by indentation methods

2020 ◽  
Vol 2020 (01) ◽  
pp. 98-113
Author(s):  
O. Grigoriev ◽  
◽  
L. Melakh ◽  
T. Mosina ◽  
N. Brodnikovsky ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Crack Resistance ◽  
Thermal Stresses ◽  
Ceramic Composites ◽  
Strength Properties ◽  
Composites Manufacturing ◽  
Young’S Moduli ◽  
Layered Ceramics ◽  
Indentation Methods ◽  
Elastic Characteristics

Technology and modes of ZrB2―SiC layered ceramic composites manufacturing have been developed. The structures, elastic characteristics and strength properties of the materials under investigation have been studied. Effect of internal stress fields on fracture processes in the indentation area and mechanical properties of the ceramics in its microvolumes has been investigated both in layers and at their interfaces. Using values of contact tensile strength along different directions in layers of the composites, effective residual thermal stresses have been calculated (≈180 MPa). The obtained data on contact tensile strength and effective crack resistance, taking into consideration the contributions of residual stresses to their values, have been used for estimations of contact strength and crack resistance of the layer materials themselves. The fracture toughness measured by the three-point bending method is 3,3—3,7 MPa · m1/2. Analysis of the data obtained indicates that the spark notch provides a greater sharpness of the crack tip and better conditions for measuring K1c, while processing with a blade picks up a sharp thermal crack in the notch tip. The elastic properties of the multilayer system (SiC—15% ZrB2) + (SiC—30% ZrB2) were studied using ultrasonic research methods. The values of the velocities of sound and elastic characteristics are sufficiently large and close to those expected from the models of the composite, which does not contain noticeable porosity and microcracks in the layers themselves and in the region of their boundaries. For directions along and across the plane of the layers, the values of Young's moduli differ by about 6%. For the directions of propagation of an ultrasonic wave along and across the layers, anisotropy of ultrasonic velocities of ~5% and elastic moduli of ~10—12% is observed, which may be due to the texture that develops in the structure of the layers during hot pressing. Keywords: layered ceramics, indentation, strength properties, thermal stresses.

Structural Material Trends in Future Power Plants

2000 ◽  
Vol 122 (3) ◽  
pp. 256-258 ◽  
Author(s):  
Horst Hack
Keyword(s):  
High Temperature ◽  
High Performance ◽  
Power Plants ◽  
Ceramic Matrix Composites ◽  
Ceramic Composites ◽  
Strength Properties ◽  
Combined Cycle ◽  
Maximum Efficiency ◽  
High Temperature Strength ◽  
Matrix Composites

Environmental and economic concerns necessitate advances in power generation technology. Future power plants will be more fuel efficient, environmentally benign, and economical than current power plants. A high performance power system (HIPPS), based on a coal-fired combined cycle, is currently being developed. The corrosion and temperature-strength properties of currently available metallic materials limit the maximum efficiency of this cycle. Recently, ceramic matrix composites have shown promise in overcoming the design limitations on future power plants. In particular, the high-temperature strength, and corrosion and erosion resistant properties of continuous fiber ceramic composites (CFCCs) will allow engineers to design high-temperature heat exchangers, cyclone vortex finder tubes, and other components. Research is being performed to evaluate candidate materials for use in future power plants. [S0094-4289(00)00203-6]

Microstructure and Properties of the Composites: Hydroxyapatite With Addition of Zirconium Phase

2009 ◽  
Author(s):  
Agata Dudek ◽  
Adam Tokarz
Keyword(s):  
Solid Solution ◽  
Ceramic Composites ◽  
Strength Properties ◽  
Animal Body ◽  
Microstructure And Properties ◽  
Recent Trends

The group of bioceramics include hydroxyapatites, which, due to their specific properties, are widely used in biotechnology. These compounds exist in skeleton of human and animal body. A range of advantages of implants which contain, among other things, hydroxyapatites, results also from the level of their porosity. Recent trends that focus on improvement in poor strength properties of HAp coatings include introduction of solid solution of Y2O3 in ZrO2 [1–7]. It seems to be essential to determine the resulting structural and strength properties in the aspect of further application of composites based on hydroxyapatite with addition of zirconium phase. The investigations involved ceramic composites based on HAp with different amounts of the phase modified with ZrO2 yttrium dioxide.

SEM Study of Tension Wood Fiber Morphology and its Effect on Paper Properties

1977 ◽  
Vol 35 ◽  
pp. 308-309
Author(s):  
K. W. Robinson
Keyword(s):  
Tension Wood ◽  
Wood Fiber ◽  
Strength Properties ◽  
Fiber Morphology ◽  
Paper Properties ◽  
Pure Cellulose ◽  
Short Rotation ◽  
Hardwood Trees ◽  
Sem Study

Tension wood (TW) is an abnormal tissue of hardwood trees; although it has been isolated from most parts of the tree, it is frequently found on the upper side of branches and leaning stems. TW has been classically associated with geotropic alignment, but more recently it has been associated with fast growth. Paper made from TW is generally lower in strength properties. Consequently, the paper industries' growing dependence on fast growing, short- rotation trees will result in higher amounts of TW in the final product and a corresponding reduction in strength.Relatively few studies have dealt with the role of TW in the structure of paper. It was suggested that the lower strength properties of TW were due to a combination of factors, namely, its unique morphology, compression failures in the cell wall, and lower hemicellulose content. Central to the unique morphology of the TW fiber is the thick gelatinous layer (G-layer) composed almost entirely of pure cellulose.

Microstructural Evaluation of Silicon Carbide Whisker Reinforced Alumina Fabricated with Carbon-Coated Whiskers

1991 ◽  
Vol 49 ◽  
pp. 920-921
Author(s):  
K. B. Alexander ◽  
P. F. Becher
Keyword(s):  
Silicon Carbide ◽  
High Resolution Electron Microscopy ◽  
Ceramic Composites ◽  
Interface Debonding ◽  
Resolution Electron ◽  
Microstructural Evaluation ◽  
Carbon Coated ◽  
Electron Energy Loss ◽  
Interfacial Films ◽  
Debonding Process

The presence of interfacial films at the whisker-matrix interface can significantly influence the fracture toughness of ceramic composites. The film may alter the interface debonding process though changes in either the interfacial fracture energy or the residual stress at the interface. In addition, the films may affect the whisker pullout process through the frictional sliding coefficients or the extent of mechanical interlocking of the interface due to the whisker surface topography.Composites containing ACMC silicon carbide whiskers (SiCw) which had been coated with 5-10 nm of carbon and Tokai whiskers coated with 2 nm of carbon have been examined. High resolution electron microscopy (HREM) images of the interface were obtained with a JEOL 4000EX electron microscope. The whisker geometry used for HREM imaging is described in Reference 2. High spatial resolution (< 2-nm-diameter probe) parallel-collection electron energy loss spectroscopy (PEELS) measurements were obtained with a Philips EM400T/FEG microscope equipped with a Gatan Model 666 spectrometer.

HREM interface studies in SiC-whisker-reinforced Al2O3 and Si3N4 ceramics

1988 ◽  
Vol 46 ◽  
pp. 734-735
Author(s):  
W. Braue ◽  
R.W. Carpenter ◽  
D.J. Smith
Keyword(s):  
Analytical Data ◽  
Base Material ◽  
High Strength ◽  
Ceramic Composites ◽  
Good Thermal Stability ◽  
All Ceramic ◽  
Sic Whiskers ◽  
Base Composite ◽  
C 30 ◽  
Si3n4 Ceramics

Whisker and fiber reinforcement has been established as an effective toughening concept for monolithic structural ceramics to overcome limited fracture toughness and brittleness. SiC whiskers in particular combine both high strength and elastic moduli with good thermal stability and are compatible with most oxide and nonoxide matrices. As the major toughening mechanisms - crack branching, deflection and bridging - in SiC whiskenreinforced Al2O3 and Si3N41 are critically dependent on interface properties, a detailed TEM investigation was conducted on whisker/matrix interfaces in these all-ceramic- composites.In this study we present HREM images obtained at 400 kV from β-SiC/α-Al2O3 and β-SiC/β-Si3N4 interfaces, as well as preliminary analytical data. The Al2O3- base composite was hotpressed at 1830 °C/60 MPa in vacuum and the Si3N4-base material at 1725 °C/30 MPa in argon atmosphere, respectively, adding a total of 6 vt.% (Y2O3 + Al2O3) to the latter to promote densification.

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